| MadSci Network: Astronomy |
Craig, The short answer is - you could save the External Tanks (ETs) in orbit and use them for other things. However, it doesn't come for free. One thing is that when the main engines of the shuttle shut off, it is still not in its final orbit. They jettison the fuel tank at this point, but they have to do another burn with the smaller Orbital Maneuvering System (OMS) engines which carry their own fuel. This burn does not occur until 45 min or so after separation from the ET. To Save the ET in orbit, it would have to stay attached to the shuttle, therefore making the whole system heavier for the OMS burn to finalize the orbit. Also, once the shuttle jettisons the tank, it would need to have it's own control system to keep it stable and keep it boosted so it wouldn't eventually fall back to earth. Then, of course, you need to get inside the tank, empty any remaining fuel, construct various living/working quarters in it, etc. It's interesting to know that there were (are?) many designs for using the tanks as building blocks for space stations. You can see some of them here: http://www.spaceislandgroup.com/geode-history.html -Steve
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